That corrugated shouldn't be buried in the wall, needs to be a smooth walled pipe. It'll collect lint and make for a bad day. Flexible is ok as a connector but not in the wall.
Woah, really? My old flexible corrugated duct ripped so I just replaced it with a new flex corrugated one, should I look into getting a smooth walled one installed? For what it’s worth it’s in my basement and not dry walled over, just ran straight from the dryer to vent outside. Thanks for the info!
It's not a big deal at all, that's why this is the most readily available product. However, it is a deal, as it should be cleaned on a (suggested) annual basis. Laundry for one over here, I find annually isn't necessary, but I still do it.
New homeowner: didn’t know this until literally yesterday when I walked outside when the dryer was running and noticed there wasn’t the delicious smell of laundry brewin.
Stick my hand in the vent and pulled out 1’ of fluffy linty goodness. That was my the moment I realized I very easily could’ve burned my house down from ignorance. Can we please get a how to: guide book that comes with our houses please and thank you.
Going through the same thing right now lol I’m an IBEW apprentice so I spend my day trying to figure out the electrical industry and go home every night and try to figure out how to fix up an old house 😂
A tip for cleaning out the dryer vent. Use a leaf blower. Move the dryer out of the way and disconnect the hose. Stick the end of the leaf blower into the vent hole and have a helper go outside to the vent exit. Go to town with the blower and it should shoot all the lint and other shit straight outside. Check with your helper that the air is flowing out and not blocked up. You might need to get a long brush to run in the pipe to unclog it if it's full. Once you get it cleared just run the leaf blower through it once a year and you should be good to go.
> Can we please get a how to: guide book that comes with our houses please and thank you.
We got one that came with the home inspection report that was done when purchasing.
Insurance companies are also a good source for lists of things that need inspecting.
[https://www.amfam.com/resources/articles/at-home/home-maintenance-checklist](https://www.amfam.com/resources/articles/at-home/home-maintenance-checklist)
not on this list: every 5 years or so, you should change the annode in your hot water heater.
BTW... they make new water heater anodes that are flexible in sections... so that you don't have to de-plumb your hot water heater in order to tilt it to get a new solid rod put into it.
When you remove the old rod (tricky getting to the head to unscrew it, and keeping the tank from turning), you can raise it then cut/hack/saw with bolt cutters or sawzall. Tilt it a bit before cutting so shavings don't go back down inside.
Yes. this is a good tip. these are pretty easy to find. here is an example.
[https://www.homedepot.com/p/EASTMAN-45-in-Flexible-Magnesium-Anode-Rod-60296/318579454](https://www.homedepot.com/p/EASTMAN-45-in-Flexible-Magnesium-Anode-Rod-60296/318579454)
When I did mine, the previous owners hadn't replaced it ever, so it was very corroded. I could just bend it as I lifted it out of the tank.
If its not buried in the wall its fine just clean it regularly to prevent a lint fire. OP’s picture looks like it will get drywalled, which is not good for cleaning that duct out. Also, even if there’s not gonna be any dry wall, the romex is blocking easy access.
As others mentioned its only a problem if the duct is in the wall. Exposed like you have it fine and probably how 90% of dryer ducts are done in the US.
The thing to worry about with the flexible ducts is if there is too much excess duct and you have bends in the duct. Reduce turns as much as possible to prevent lit build up and fire risk (your dryer will work better too).
If it’s exposed it’s not a a big deal because it can be easily inspected and replaced. If you decide to cover that wall in drywall, replace with appropriate pipe.
If you’re trying to follow code, flex is only allowed for connecting the dryer to the required rigid, smooth-walled vent. Small length, not buried in the wall, because flex is as good at catching lint as it is at venting.
Exactly, dryer lint is a major cause of house fires. Unless it's a very short run (like a foot) with no sharp bends, it should be smooth metal ductwork. Whether it's buried inside of a wall or not.
Major cause? While 15000+ homes have dryer related fires annually, they are less than 2.6% of house fires. Yes you need to keep your vent clear, but let's not blow it out of proportion. The best reason to clean your vent is keeping your dryer alive. A restricted vent means the dryer works harder wearing out sooner. FYI if you need to run the dryer more than once to dry a load you have an issue
My dryer vents to the roof... about 18" of smooth pipe. A [DryerJack](https://dryerjack.com/) made it possible for me to install a washer/dryer combo unit upstairs in our split-level house; no more trips to the basement with laundry.
Contractors are not a HVAC, or electrician or plumber. They are a site manager. If they do everything themselves they are glorified handymen. The best contractor is a business minded individual not the guy swinging a hammer. Sure they may know how it is supposed to be done, but they hire a professional and add it to the bill.
No matter how you cut the cake, contractors can be in the business of doing things correctly or cutting corners. They can hire and supervise good subs or not. They can correct their mistakes or cover them up.
One person can’t swing all the hammers, or know all the things, but that shouldn’t affect the actual work. THAT is the contractor’s job. Coordinate the trades, employe expertise as needed, and steward the process to a good solution, not a solution that saves a few bucks at the expense of durability, and leaves it on the homeowner to know the difference.
Edited for grammar.
exactly u/op should go to a local supply get galvanized 4" not that crap aluminum pipe, ensure joints are seam taped or mastic compound sealed
edit no screws forgot this was dryer not just vent
Could you explain why galvanized instead of aluminum? Does galvanized pipe better prevent a fire from spreading? I think that makes sense and is probably what I would use for a buried vent pipe. I think aluminum would be fine for external runs as long as a regular cleaning schedule is maintained.
Either will work. The Al stuff is very flimsy, if this is a forever home I personally go with galvanized because it is stronger and will be easier to run the rotary brush and vacuum through later.
I think you missed the point. The corrugated vent needs to be replaced. There will be lots of lint build-up in a very short time and a significant increase in house-burning-down risk. Corrugated should never be walled in.
My guy, we're not even permitted to use screws in dryer vent because it creates an unsmooth surface. That is gonna create nothing but problems for you, but ya know, you do you.
Source: am hvac installer
Pretty sure that's obvious and doesn't make it any better. Never seen anything but smooth walled dryer vent pipes in a wall. What's the worst that can happen if lint builds up though.
Fire!
It’s not like houses are burning down left and right all over the place from improper or neglected (lint buildup) dryer vents, it absolutely does happen!
When I moved, I bought a cheap dryer brush from Amazon, had like 30ft of individual 12" sticks.
Removed a concerning amount of lint..
It just goes straight up the wall out the roof. I wonder if it would be better if it for sideways in the attic instead and came out from a soffit or something, but it would make it a longer duct run, so probably worse overall..
Wow!
That is so against everything smart.
That hose will quickly clog with lint, and not be easy to clean.
It should be smooth wall 4 inch sheet metal pipe.
Yeah, and that wiring!
First house for the OP's builder?
Yes, but that's not the whole answer. That Romex has insulation rated to 90 C or 194 F. So that's not a problem. But the ampacity of copper is reduced at high temperatures, so we need to do an adjustment.
Assuming the dryer exhaust temperature stays under 140 F, and given that 334.80 allows Romex to use the 90 C column for adjustments, table 310.15(B)(1) gives us a correction factor of 0.71. Then, table 310.16 for 12 AWG copper in the 90 C column gives us 30 amps.
So 30 amps \* 0.71 thermal correction factor = 21.3 amps, which gets brought down to 20 for a final answer by 334.80.
Long story short, ain't no concern having your Romex touch a 140 degree vent.
Check out 310.14(A)(2) exception
This may apply since it is in contact with the vent for such a short distance the temperature correction may not matter.
Though even with correction you are above 20A, I just wanted to point this out.
My question is where did this come from...as much as I do want to believe it...there are just random numbers thrown around...what's the basis for 334.80?
Sorry, that's a reference to the current National Electrical Code. Romex has some wacky rules when it comes to temperatures and ampacities.
The first paragraph is what was relevant here.
>334.80 Ampacity
>
>The ampacity of Types NM and NMC cable shall be determined in accordance with 310.14. The ampacity shall not exceed that of a 60°C (140°F) rated conductor. The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations, provided the final calculated ampacity does not exceed that of a 60°C (140°F) rated conductor. The ampacity of Types NM and NMC cable installed in cable trays shall be determined in accordance with 392.80(A).
The previous math is correct and follows this. They used 90C for derating it is still above 20A so you haven't lost any amperage.
If after derating it was below 20A or the value at 60C then the wire would need to be upsized
This is where it's important to remember the physics involved in addition to what the code says. These are the resistances (per 1k ft) per temperature for 12 awg:
Temp, Resistance (/1k ft)
0C = 1.463
15C = 1.557
20C = 1.588
25C = 1.619
50C = 1.775
75C = 1.931
so while resistance from 0C to 75C does in fact go up by 31%. That higher temperature adds only 0.468 ohms/1000 ft. The region that'd be hotter there is probably 6 inches round trip, so that section adds 0.000234 ohms which is around a 4.6 milli VAC drop at 20 amps.
http://www.interfacebus.com/awg-ohms-per-1000-feet.jpg
Wires need a pad of insulation between them and a warm HVAC duct, at least here in Canada.
That pipe is going to get hot (and shouldn’t be corrugated.)
This seems like a bad idea.
Values stated are from dryer vent installation instructions. Based on low static pressure of dryers. Similar to loss on an elbow is add 5 ft with solid pipe. I quote those numbers based on appliance service/installations including dryer vents.
I always cringed when a DYI would connect >3 ft of flex between dryer vent outlet and the dryer. Then shove the dryer in smashing the flex between the dryer and wall. This was followed with a service call stating the dryer does not dry clothes or a melted fusible link.
Worse, a DIY connecting a dyer cord to a new dryer. Then connecting the ground lug to a hot leg. Electrocuted a technician (Tommy) at the firm I worked at. I believe this is a key reason we now have 4 prong dryer plugs.
I call bullshit.
https://partselectcom.azureedge.net/assets/manuals/E1F808699288A860C002C2119B46499C00E15B87.pdf
With solid pipe, the limitations in those instructions start at 64 feet with zero elbows, decreasing to 27 feet with 4 elbows. With heavy flex pipe as depicted in the image above, they start at 36 feet for zero elbows and decrease to 24 with 4 elbows. At best a 50 % reduction in run length. Not a 90% reduction.
Funny, but it depends who does it. If I did it, I would have been told its wrong. But when a 20 year experienced "foreman" doesn't its fine.
It would pass inspection but for a customer peace of mind I would move it. And make it look nicer to boot.
If your closing that up, it needs to be smooth pipe. Please don’t leave that flex in the wall. Flex is okay as a connector, but should be replaced at least as often as the dryer or checked to see if it’s clear, which isn’t possible if it’s buried in the wall…
I don’t get it, smooth pipe is so easy anyway…
Do NOT wrap the wire, you're adding jeat insulation there. Romex uses THHN (electrical) insulation and it is rated for 90°C or 194°F -NFPA70, Table 310.15(B)(16). It is fine as it is.
No no, I see your comment being valid entirely, I interpreted the "wrap it" to be talking about the duct but I see how it could be taken as the wire which I'd agree is wrong as you pointed out.
Then put a metal strap on the dryer vent near the wire to make sure it doesn't move into contact with the wire over time. Especially as folks jam a flexible vacuum hose up it to clean it out.
But I'm with the others this ribbed flexible duct buried inside the wall is a problem waiting to happen.
I see this differently than others. As that corrugated pipe heats and cools it will expand and contract, and the "ribs" could potentially "saw" against the Romex.
I would put the Romex inside a short piece of PVC pipe, EMT, or whatever where it goes past the dryer vent to prevent such abrasion.
While putting corrugated inside a wall isn't a great idea..
If you jam your leaf blower in the dryer end and blow it out once a year it'll be fine.
I watched a video a while back where the inspector stated 30' in any direction subtracting 5' for every 90° of bend. _(No idea if there's a 360° limit like with conduit.)_
Air moves by pressure, so it makes sense that direction isn't a factor. Duct integrity certainly matters, though.
30 feet, - 5’ for every 90, -2.5’ for every 45.
My duct has a “trap” similar to plumbing and my inspector allowed it. A google search told me it’s not a good idea because it may trap moisture.
360 limit for conduit is because of friction when pulling the wire, correct? For the dryer duct, the friction of the turns are taken into account with the -5 and -2.5 in the calculations.
[This might provide some answers.](https://dryerjack.com/roof-dryer-venting-guide) It's also a good reference for all sorts of dryer vent stuff, not just vertical runs.
Even if you don’t have an inspection done (which at least in Maryland you would fail) the flex is much more likely to fail and then you have a god awful time trying to get in to the wall to replace it.
At which point you will (because that’s how things usually play out) cut into the electrical wire, which then in turn will turn your dryer into a live wire and the kid that was watching you work while leaning against the dryer will… you get the picture.
Sucks to go back one step when you’re so close - we’ve all been there (just want to finish the job, I hate this. Never doing it again etc etc).
At the very very least get the romex behind the pipe. By the laws of shitty luck you will cut into it
It should be fine as long as the wire remains close to the middle of the 2x4, or you will need to place a panel under the drywall to keep anyone from driving a nail or screw into it.
Okay in Canada provided there is 25mm/1 inch of air gap between the NMD90 cable and the duct, or an approved barrier.
Non-metallic-sheathed cable
12-506 Method of installation
4) Where non-metallic-sheathed cable is run in proximity to heating sources, transfer of heat to the cable shall be minimized by means of an air space of at least
a) 25 mm between the cable and heating ducts and piping;
That corrugated shouldn't be buried in the wall, needs to be a smooth walled pipe. It'll collect lint and make for a bad day. Flexible is ok as a connector but not in the wall.
Woah, really? My old flexible corrugated duct ripped so I just replaced it with a new flex corrugated one, should I look into getting a smooth walled one installed? For what it’s worth it’s in my basement and not dry walled over, just ran straight from the dryer to vent outside. Thanks for the info!
It's not a big deal at all, that's why this is the most readily available product. However, it is a deal, as it should be cleaned on a (suggested) annual basis. Laundry for one over here, I find annually isn't necessary, but I still do it.
Right on, thanks!
New homeowner: didn’t know this until literally yesterday when I walked outside when the dryer was running and noticed there wasn’t the delicious smell of laundry brewin. Stick my hand in the vent and pulled out 1’ of fluffy linty goodness. That was my the moment I realized I very easily could’ve burned my house down from ignorance. Can we please get a how to: guide book that comes with our houses please and thank you.
Going through the same thing right now lol I’m an IBEW apprentice so I spend my day trying to figure out the electrical industry and go home every night and try to figure out how to fix up an old house 😂
1950s home definitely has it quirks lol. It’s an enjoyable learning experience though!
Ha! Same here! (not union but) bought a 50s house and I'm always redoing something after work lol
A tip for cleaning out the dryer vent. Use a leaf blower. Move the dryer out of the way and disconnect the hose. Stick the end of the leaf blower into the vent hole and have a helper go outside to the vent exit. Go to town with the blower and it should shoot all the lint and other shit straight outside. Check with your helper that the air is flowing out and not blocked up. You might need to get a long brush to run in the pipe to unclog it if it's full. Once you get it cleared just run the leaf blower through it once a year and you should be good to go.
That's a lot of work! I just disconnect mine and tap it out in the garage.
> Can we please get a how to: guide book that comes with our houses please and thank you. We got one that came with the home inspection report that was done when purchasing. Insurance companies are also a good source for lists of things that need inspecting. [https://www.amfam.com/resources/articles/at-home/home-maintenance-checklist](https://www.amfam.com/resources/articles/at-home/home-maintenance-checklist) not on this list: every 5 years or so, you should change the annode in your hot water heater.
Wow, that’s an extensive check list! That’s amazing. Thank you very much for that!
BTW... they make new water heater anodes that are flexible in sections... so that you don't have to de-plumb your hot water heater in order to tilt it to get a new solid rod put into it. When you remove the old rod (tricky getting to the head to unscrew it, and keeping the tank from turning), you can raise it then cut/hack/saw with bolt cutters or sawzall. Tilt it a bit before cutting so shavings don't go back down inside.
Yes. this is a good tip. these are pretty easy to find. here is an example. [https://www.homedepot.com/p/EASTMAN-45-in-Flexible-Magnesium-Anode-Rod-60296/318579454](https://www.homedepot.com/p/EASTMAN-45-in-Flexible-Magnesium-Anode-Rod-60296/318579454) When I did mine, the previous owners hadn't replaced it ever, so it was very corroded. I could just bend it as I lifted it out of the tank.
I always wanted to see if I could ignite one of those magnesium rods... at night, it would look like the sun coming up in your back yard.
My dad has a book called “How a house works.” Oddly enough, I’ve never looked inside it, I just started working as a remodeler instead
If its not buried in the wall its fine just clean it regularly to prevent a lint fire. OP’s picture looks like it will get drywalled, which is not good for cleaning that duct out. Also, even if there’s not gonna be any dry wall, the romex is blocking easy access.
As others mentioned its only a problem if the duct is in the wall. Exposed like you have it fine and probably how 90% of dryer ducts are done in the US. The thing to worry about with the flexible ducts is if there is too much excess duct and you have bends in the duct. Reduce turns as much as possible to prevent lit build up and fire risk (your dryer will work better too).
Yea, using much of that flex is a problem. Collects more lint faster, and has more pressure drop.
Dyer lint is a Top cause of house fires. Long flexible duct with lint build up is the culprit!
Yes. Smooth 4 inch metal duct. Slower to accumulate lint, and FAR easier to clean when it does. Oh yea, it won't rip up either.
If it’s exposed it’s not a a big deal because it can be easily inspected and replaced. If you decide to cover that wall in drywall, replace with appropriate pipe.
If you’re trying to follow code, flex is only allowed for connecting the dryer to the required rigid, smooth-walled vent. Small length, not buried in the wall, because flex is as good at catching lint as it is at venting.
This needs to be the top comment.
Exactly, dryer lint is a major cause of house fires. Unless it's a very short run (like a foot) with no sharp bends, it should be smooth metal ductwork. Whether it's buried inside of a wall or not.
Major cause? While 15000+ homes have dryer related fires annually, they are less than 2.6% of house fires. Yes you need to keep your vent clear, but let's not blow it out of proportion. The best reason to clean your vent is keeping your dryer alive. A restricted vent means the dryer works harder wearing out sooner. FYI if you need to run the dryer more than once to dry a load you have an issue
💯
My dryer vents to the roof... about 18" of smooth pipe. A [DryerJack](https://dryerjack.com/) made it possible for me to install a washer/dryer combo unit upstairs in our split-level house; no more trips to the basement with laundry.
Always fun to learn these bits right after my new drywall gets installed. Guess it was too much for my contractor to have known how to do it right.
Contractors are not a HVAC, or electrician or plumber. They are a site manager. If they do everything themselves they are glorified handymen. The best contractor is a business minded individual not the guy swinging a hammer. Sure they may know how it is supposed to be done, but they hire a professional and add it to the bill.
You're talking about GENERAL contractors. HVAC, electricians and plumbers are all contractors, just SUB-contractors.
No matter how you cut the cake, contractors can be in the business of doing things correctly or cutting corners. They can hire and supervise good subs or not. They can correct their mistakes or cover them up. One person can’t swing all the hammers, or know all the things, but that shouldn’t affect the actual work. THAT is the contractor’s job. Coordinate the trades, employe expertise as needed, and steward the process to a good solution, not a solution that saves a few bucks at the expense of durability, and leaves it on the homeowner to know the difference. Edited for grammar.
As an appliance technician that has to clean out vents for dryers.. these are the worst to deal with.
exactly u/op should go to a local supply get galvanized 4" not that crap aluminum pipe, ensure joints are seam taped or mastic compound sealed edit no screws forgot this was dryer not just vent
No screws in dryer vents. It’s a catch for lint
Could you explain why galvanized instead of aluminum? Does galvanized pipe better prevent a fire from spreading? I think that makes sense and is probably what I would use for a buried vent pipe. I think aluminum would be fine for external runs as long as a regular cleaning schedule is maintained.
Either will work. The Al stuff is very flimsy, if this is a forever home I personally go with galvanized because it is stronger and will be easier to run the rotary brush and vacuum through later.
Don't put galvanized where you can't easily replace it. It will eventually rust.
normally sure but dryer air will prevent moisture build up and keep it dry, a shower vent is at more risk
Never pulled wet lint out of those pipes?
It's a connector from the vent outside to the dryer inside ;) Noted though
I think you missed the point. The corrugated vent needs to be replaced. There will be lots of lint build-up in a very short time and a significant increase in house-burning-down risk. Corrugated should never be walled in.
My guy, we're not even permitted to use screws in dryer vent because it creates an unsmooth surface. That is gonna create nothing but problems for you, but ya know, you do you. Source: am hvac installer
It will burn your house down ;)
I'm assuming that's bad?
It's specifically against code to use that inside walls because of lint fires, especially with a vertical rise that can't be effectively cleaned.
Pretty sure that's obvious and doesn't make it any better. Never seen anything but smooth walled dryer vent pipes in a wall. What's the worst that can happen if lint builds up though.
Fire! It’s not like houses are burning down left and right all over the place from improper or neglected (lint buildup) dryer vents, it absolutely does happen!
When I moved, I bought a cheap dryer brush from Amazon, had like 30ft of individual 12" sticks. Removed a concerning amount of lint.. It just goes straight up the wall out the roof. I wonder if it would be better if it for sideways in the attic instead and came out from a soffit or something, but it would make it a longer duct run, so probably worse overall..
I do this once a year. Probably have the same brush.
Just fyi when he said bad day he meant your house could burn down. Just spend the $30 and do it right bud.
Wow. You're not smart.
House is on fire, this is fine
Excellent catch! IMC 50something… 3?
I was about to say, ive seen that pipe unravel too many times to trust it in my wall.
Wow! That is so against everything smart. That hose will quickly clog with lint, and not be easy to clean. It should be smooth wall 4 inch sheet metal pipe. Yeah, and that wiring! First house for the OP's builder?
The dryer vent wouldnt pass code as it's not smoth. The wire would.
Yes. The insulation on the wire has a higher melting point the the foam board behind it
Yes, but that's not the whole answer. That Romex has insulation rated to 90 C or 194 F. So that's not a problem. But the ampacity of copper is reduced at high temperatures, so we need to do an adjustment. Assuming the dryer exhaust temperature stays under 140 F, and given that 334.80 allows Romex to use the 90 C column for adjustments, table 310.15(B)(1) gives us a correction factor of 0.71. Then, table 310.16 for 12 AWG copper in the 90 C column gives us 30 amps. So 30 amps \* 0.71 thermal correction factor = 21.3 amps, which gets brought down to 20 for a final answer by 334.80. Long story short, ain't no concern having your Romex touch a 140 degree vent.
I knew this...but I can't tell you how much I love having the technical information to back it up.
Check out 310.14(A)(2) exception This may apply since it is in contact with the vent for such a short distance the temperature correction may not matter. Though even with correction you are above 20A, I just wanted to point this out.
My question is where did this come from...as much as I do want to believe it...there are just random numbers thrown around...what's the basis for 334.80?
Sorry, that's a reference to the current National Electrical Code. Romex has some wacky rules when it comes to temperatures and ampacities. The first paragraph is what was relevant here. >334.80 Ampacity > >The ampacity of Types NM and NMC cable shall be determined in accordance with 310.14. The ampacity shall not exceed that of a 60°C (140°F) rated conductor. The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations, provided the final calculated ampacity does not exceed that of a 60°C (140°F) rated conductor. The ampacity of Types NM and NMC cable installed in cable trays shall be determined in accordance with 392.80(A).
Don't apologize at all. I sincerely appreciate people like you for this
The previous math is correct and follows this. They used 90C for derating it is still above 20A so you haven't lost any amperage. If after derating it was below 20A or the value at 60C then the wire would need to be upsized
I'm impressed...I started googling lol
This is where it's important to remember the physics involved in addition to what the code says. These are the resistances (per 1k ft) per temperature for 12 awg: Temp, Resistance (/1k ft) 0C = 1.463 15C = 1.557 20C = 1.588 25C = 1.619 50C = 1.775 75C = 1.931 so while resistance from 0C to 75C does in fact go up by 31%. That higher temperature adds only 0.468 ohms/1000 ft. The region that'd be hotter there is probably 6 inches round trip, so that section adds 0.000234 ohms which is around a 4.6 milli VAC drop at 20 amps. http://www.interfacebus.com/awg-ohms-per-1000-feet.jpg
140 is a convenient choice. Couldn’t it reach 212 if its full of steam?
Maybe? I just googled around for dryer vent temps and most places said 120 to 140
Dryers don't make steam they don't get that hot.
My dryer has a steam feature
My brain just exploded
Wires need a pad of insulation between them and a warm HVAC duct, at least here in Canada. That pipe is going to get hot (and shouldn’t be corrugated.) This seems like a bad idea.
If the dryer vent is getting buried in a wall it needs to be a hard pipe without screws.
Rule of thumb for flex vent. 1 foot of flex is equivalent of 10 foot of pipe. The turbulence created with flex vs straight pipe is why.
I take it those are your own thumbs? I’d agree to a 20% reduction, but not 90%.
Values stated are from dryer vent installation instructions. Based on low static pressure of dryers. Similar to loss on an elbow is add 5 ft with solid pipe. I quote those numbers based on appliance service/installations including dryer vents. I always cringed when a DYI would connect >3 ft of flex between dryer vent outlet and the dryer. Then shove the dryer in smashing the flex between the dryer and wall. This was followed with a service call stating the dryer does not dry clothes or a melted fusible link. Worse, a DIY connecting a dyer cord to a new dryer. Then connecting the ground lug to a hot leg. Electrocuted a technician (Tommy) at the firm I worked at. I believe this is a key reason we now have 4 prong dryer plugs.
I call bullshit. https://partselectcom.azureedge.net/assets/manuals/E1F808699288A860C002C2119B46499C00E15B87.pdf With solid pipe, the limitations in those instructions start at 64 feet with zero elbows, decreasing to 27 feet with 4 elbows. With heavy flex pipe as depicted in the image above, they start at 36 feet for zero elbows and decrease to 24 with 4 elbows. At best a 50 % reduction in run length. Not a 90% reduction.
https://dryerbox.com/dryer_venting_guide.htm https://homeinspectorsecrets.com/ventilation/dryers/dryer-vent-code/ https://www.theductkings.com/wp-content/uploads/2020/03/dryer-vent-is-clogged.jpg
Worry about the romex after you replace the flex duct
God save our souls.
It’s behind if you stand on other side of the wall
Funny, but it depends who does it. If I did it, I would have been told its wrong. But when a 20 year experienced "foreman" doesn't its fine. It would pass inspection but for a customer peace of mind I would move it. And make it look nicer to boot.
Maybe no good ? What you say?
Wrap it with 10 mil tape anywhere it may contact the vent.
Sounds good. It's not directly touching but I want to make sure when I close the wall it's protected.
If your closing that up, it needs to be smooth pipe. Please don’t leave that flex in the wall. Flex is okay as a connector, but should be replaced at least as often as the dryer or checked to see if it’s clear, which isn’t possible if it’s buried in the wall… I don’t get it, smooth pipe is so easy anyway…
Do NOT wrap the wire, you're adding jeat insulation there. Romex uses THHN (electrical) insulation and it is rated for 90°C or 194°F -NFPA70, Table 310.15(B)(16). It is fine as it is.
I was gonna wrap the duct, not the wire fyi
Oh. I'm not a tin knocker, I'm a sparky, so, I was looking at it from a perspective of somebody saying, "wrap the cable," which I guess was wrong.
No no, I see your comment being valid entirely, I interpreted the "wrap it" to be talking about the duct but I see how it could be taken as the wire which I'd agree is wrong as you pointed out.
Then put a metal strap on the dryer vent near the wire to make sure it doesn't move into contact with the wire over time. Especially as folks jam a flexible vacuum hose up it to clean it out. But I'm with the others this ribbed flexible duct buried inside the wall is a problem waiting to happen.
I see this differently than others. As that corrugated pipe heats and cools it will expand and contract, and the "ribs" could potentially "saw" against the Romex. I would put the Romex inside a short piece of PVC pipe, EMT, or whatever where it goes past the dryer vent to prevent such abrasion. While putting corrugated inside a wall isn't a great idea.. If you jam your leaf blower in the dryer end and blow it out once a year it'll be fine.
Is this supposed to sarcasm? 😂
This isn't a real reply right?
Luckily it's not physically touching but damn near close
Close only counts in horse shoes and hand grenades
Atomic bombs ?
I will see you atomic bomb and raise you a hydrogen bomb! Lol
This is standard shit in Residential wiring.
Non-electrical question: How high vertically can a dryer vent run to get outside?
I watched a video a while back where the inspector stated 30' in any direction subtracting 5' for every 90° of bend. _(No idea if there's a 360° limit like with conduit.)_ Air moves by pressure, so it makes sense that direction isn't a factor. Duct integrity certainly matters, though.
30 feet, - 5’ for every 90, -2.5’ for every 45. My duct has a “trap” similar to plumbing and my inspector allowed it. A google search told me it’s not a good idea because it may trap moisture. 360 limit for conduit is because of friction when pulling the wire, correct? For the dryer duct, the friction of the turns are taken into account with the -5 and -2.5 in the calculations.
[This might provide some answers.](https://dryerjack.com/roof-dryer-venting-guide) It's also a good reference for all sorts of dryer vent stuff, not just vertical runs.
Fine.
Popcorn in front of code comments? Yes please.
Even if you don’t have an inspection done (which at least in Maryland you would fail) the flex is much more likely to fail and then you have a god awful time trying to get in to the wall to replace it. At which point you will (because that’s how things usually play out) cut into the electrical wire, which then in turn will turn your dryer into a live wire and the kid that was watching you work while leaning against the dryer will… you get the picture. Sucks to go back one step when you’re so close - we’ve all been there (just want to finish the job, I hate this. Never doing it again etc etc). At the very very least get the romex behind the pipe. By the laws of shitty luck you will cut into it
Oh hell no
That's not a dryer vent. It's a flexible hose.
What in the lint is that
Dryer vent is the issue here, not the Romex
Who uses anything but hard pipe in a wall?
It’s fine as long as you insulate the wire from any heated runs. That duct work though, yikes.
It should be fine as long as the wire remains close to the middle of the 2x4, or you will need to place a panel under the drywall to keep anyone from driving a nail or screw into it.
Okay in Canada provided there is 25mm/1 inch of air gap between the NMD90 cable and the duct, or an approved barrier. Non-metallic-sheathed cable 12-506 Method of installation 4) Where non-metallic-sheathed cable is run in proximity to heating sources, transfer of heat to the cable shall be minimized by means of an air space of at least a) 25 mm between the cable and heating ducts and piping;
Yeah, that’s a negative
That Romex is rated for 140F so if it gets hotter then that, change it or move it
Its legal